I just recently purchased my first Mercedes - a 1993 300E. So far I'm loving it, but I've run into one problem: the stereo. This car was one of the models that had the Becker radio w/ the control unit, amp, cd changer, etc. in the trunk. The current system is no longer working and I'm wanting to install an aftermarket stereo. I know it's a big job requiring some pretty extensive wiring, etc. and I'm fine with that, but the one thing I haven't been able to find is a decent wiring diagram for my car (I'd like to tap in to the existing speaker wires, radio power, etc.). I purchased the Mercedes Shop Manual software discs and have them installed and while they have a ton of information on my car, they don't seem to have a wiring diagram & neither does Becker. Does anyone know where I can find a wiring diagram for this car? Is there anywhere online or perhaps even a book that might have it?

Thanks in advance,
Luke

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here's a quick tutorial i will write for you
If your car has a fade control by the window controls you will want to rewire that for much better performance from there you can determine which wires are for the rear speakers. Your new aftermarket stereo will come with a wiring diagram to help you out its usually on the top of the unit. I have installed so many stereos in so many different types of cars I can guide you through it.

1. Just buy a volt meter and clip off the old wiring harness from the stock Becker. (you can get a cheap volt meter off the internet)

2. Find which wire gives the radio power while the ignition is off it will be the RED WIRE on the new stereo

* you will need to also find the ground (its usually black).

3. Turn the ignition to the ON posision and find the power wire it will be the YELLOW WIRE on the new stereo

from here you have the power taken care of, next you can wire the speakers up. if you have the fader then you will only have 4 wires to take care of they are usually color coded like green with a black line and the other wire will be green showing that they are a pair to power one speaker.

Thanks for the info! I do indeed have the console fader control (which I was planning on getting rid of and retro-fitting an aux input in its place). I think I should be good w/ the power, the antenna and the speakers, but I was hoping to tap into the power amp in the trunk to continue to power the door subs. I notice that the amp in the trunk just has one big connector block w/ all of the wires coming out of it - is there any way for me to determine which ones are the audio inputs?

almost forgot you will have a blue wire coming from the new stereo which will control your power antenna ( if yours isn't broken)

Sorry to revive this old thread. I believe someone said that usually one would need to purchase a 12' long antenna lead extension, as the current antenna lead goes to the tuner/amp in the right hand side of the trunk. And from there you need to run it up to the new head unit. Is this the only way to do it? I found it difficult to hide the long 12' antenna lead extension under the carpet, etc. Is there a speaker level wire under the fader control that I can hijack so that I can avoid running new antenna cables from the new HU to the trunk? Many thanks!

Also is it possible to leave the fader intact with aftermarket? I sort of like it.. Thanks!

Not likely. Old radio designs like the OEM one used single ended amplifiers where where the speaker outputs returned to ground. Almost all new aftermarket head units use bridged amplifier designs where both the speaker (+) and the speaker (-) carry active signal. If you try to hook a bridge design up to the fader you may damage the head unit or at the very least, you will only get 25% of the rated power output and the head unit will get very warm.

The reason for the change in design philosophy is only limited power output can be achieved on a 12 volt supply. With a single ended amplifier the theoretical true RMS power is limited to about 4 watts (with a 4 ohm load) whereas with a bridged design, the theoretical true RMS power is limited to about 16 watts. Becker and the later Bose system were know to use very low impedance speakers (2 ohms or even 1.2 ohms) to try and over come these limitations.

Most stand alone car amplifiers go back to the singled ended design (because they also contain there own internal switching power supply the provides "rail" voltages well above 12 volts), but their increased power output will vaporize the fader in a matter of minutes.

Thanks! So if I wanted to keep fader my best bert is to talk to becker for a replacement?

Please do not snip off the factory connectors as an earlier poster suggested! If you can get a suitable adapter, that’s ideal. Like if you are updating from an old 2 channel Becker to a more modern 4 channel one with modern connectors like a 1492, 1692, 2340, 2330, 4602, etc. In that case, you can use an adapter no.1163-736
But if you can’t, please just carefully tee splice into the existing wires without snipping off the factory plugs. That way it will be reversible.
Since your car is the type with the two piece radio and head unit, I would still suggest leaving all the factory wiring in place. You just need to run a few extra wires to make it work. To do this work, you’ll need to remove the wood center console panel at least. It’s probably easier to remove the whole center console.
All the needed power wires, antenna trigger wire, and the front speaker wires are still located up front. Once you hook those up, you just need to run wires to the rear speakers.

If you really want to keep the fader, you will need to repair your existing system or replace it with another old 2 channel one piece system like a 1480.

Hello, I have just become a proud owner of 190e 2.6 1993. My original car stereo died and I have bought after market stereo. Friend of mine had help me to install and now my radio is working with just two speakers (back ones). We could not figure out cable with six wire coming from car, which one is for the another two speakers ( my new radio has only four speakers option), and probably one wire must be for amplifier. That "cable" original has round connector. Please, help